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By C. A. Stetefeldt

IK the dry-crushing of ores, either by stamps, rolls, or other machinery, it is essential that the material should be free from moisture. Hence a contrivance which effects this with economy, and is of durable and compact construction, is a great desideratum. It is claimed for the below-described shelf dry-kiln, that it possesses these qualifications in a high degree. The construction of the shelf dry-kiln is based on the Hasenclever principle. That is to say, a number of inclined shelves are arranged zig-zag above each other in a vertical shaft, having openings or slits where they meet, on which the ore rests in a stratum, the thickness of which is governed by the width of the slits and the inclination of the shelves. If a portion of the charge is removed at the end of the bottom shelf, a sliding motion of the ore takes place on all shelves above, and the top shelf is replenished from a hopper set over it. It will be seen that the shaft is divided by the shelves into a number of triangular prismatic spaces. Through these the hot gases from a fireplace are made to circulate, each space communicating with the next one by a flue arranged in the sidewall of the shaft. These flues being located on alternate sides of the shaft, a continuous passage is formed through the whole structure. After thus stating the principle of the construction, its details will be easily understood by reference to the drawings, Fig. 1 to Fig. 5. The drawings, Fig. 1 to Fig. 4, represent two kilns united into one structure. The cast iron shelves(a) are 2 feet 4 inches wide and 5 feet long, with sides and a back 4 inches high, and are cast a full halfinch thick. How they rest on the brackets(d), and interlock each other, is shown in Fig. 5. Three such shelves, with an inclination of 38') are placed in one row in a brick shaft 7 feet 1/2 inch wide and 4 feet deep. The ore hoppers(g) rest on the iron bems(f). At the end of the bottom shelves are the discharge-doors(b), with shoots projecting beyond the front wall. A swinging apron(e) keeps the ore in place. By dropping it a car below the shoot is filled with dry ore. A number of extra-large pieces of ore may cause a stoppage in the slits ; for such an emergency the openings(e) are provided, through

Jan 1, 1884

By David J. Selleck, Eugene P. Pfleider

9.61. Introduction. Open pit mining methods produce more than 80% of all raw materials today in the United States. Much of this comes either from properties that formerly employed underground methods and were converted to open pit or from mines that ultimately must go underground when the economic stripping limit is reached. Generally the ores are transported over large vertical distances and techniques have been developed to do this economically. One approach is to combine conventional surface trucking, over relatively level roads, with the use of gravity and underground facilities. There are various modifications, depending upon the character of the orebody and the topography. Several schemes, as used in Sweden, Canada, and the United States, merit describing. One of the critical problems involved in the transference of ores from surface to underground is that of flow of bulk solids. Must it be crushed? Will it hang up in the transfer? What size and inclination of ore pass are required. How is the ore best fed onto the transporting device underground? As an example, the planning engineers for the Carol Project of the Iron Ore Company of Canada faced these problems in making their designs for the production and transportation of some 55,000 tpd from their Smallwood Mine in Labrador. Other operations, facing somewhat similar conditions, used other approaches of interest. This chapter describes some of the factors involved in the design, construction, and operation of a combination surface underground transportation system as applied to open pit mining operations. 9.62. Tunnel-Ore Pass Systems. The type, shape, dip, and size of the orebody, as well as the surface topographic features, generally estab-

Jan 1, 1968

By ROBERT R. RICHARDS

My. first paper, read at the Cobalt Meeting of the Institute,1 July, 1907, dealt with the behavior of a small Wilfley table when concentrating galena from quartz, the table being fed with natural products, with sized products; and with classified products. Since galena, having a specific gravity of 7.5, is among the heaviest minerals ordinarily concentrated by Wilfley table, it was desirable that a similar set of tests upon a mineral of, lighter weight should be made. Chalcopyrite, of a specific gravity of 4, would have been the best mineral for this purpose, on account of its great importance as an economic mineral, but in carrying out the test, however, I was obliged to content myself with a cupriferous pyrite, the specific gravity of which was 4.68 and the contents in copper 8.80 per cent. Through the kindness of Mr. H. 0. Cummins, this material was obtained from Shasta, Cal.,in very pure, clean, homogeneous condition. It was broken by rolls to 2 mm. in size, taking care to make a minimum of slimes. The quartz used to mix with it was pure, white, New England quartz, broken in the same way to the same size. In studying the accompanying tables, it should be borne in mind that the material concentrated was of low copper-content, and in many cases the quantity fed to the machine was 1 kg: or less.. As a consequence of the smallness of the 'quantity treated it was very difficult to adjust the table and get it in condition to do its best work before the feed became exhausted, and for this reason many results were obtained which appear irregular.

Sep 1, 1908

By W. L. Falke, A. A. Cochran

Vast deposits of low-grade manganese ore exist in the United States, yet domestic production is insignificant compared to the more than 2 million tons of ore imported yearly into this country.1 A basic problem in connection with manganese is to find economical ways to utilize domestic resources.2 As a part of its program to conserve domestic mineral resources and to reduce dependence on foreign sources, the U.S. Bureau of Mines has conducted extensive research to broaden manganese technology and to find economical processes for recovering manganese from these low-grade resources. Although a great many processes have been proposed for treating domestic manganese resources, a failing of many of them is that too many steps are involved for economical operation.2 Some of the major processes that have been proposed were reviewed by Norman and Kirby.3,4

Jan 3, 1967

By E. E. Malouf

Leaching is rapidly becoming an important adjunct to mining operations. A summary of various leaching operations is presented showing the role of these activities to the successful operation of the mining venture. The summary will include recent developments in dump, heap, and in situ leaching of copper and uranium ores. It will include a discussion on the expanding impact of industrial and academic research on leaching as a mining tool, showing the interplay of chemical kinetics and biogenic activity.

Jan 1, 1973

By Freeman Bishop

Before Capitol Hill hearings, primary metal producers are often called "concentrated industries" because there are relatively few companies in each category and most of them are large corporations. Capitol Hill still looks on large companies as inherently wrong, but there are about as many arguments one way as the other. Encourage Imports? Now comes Assistant Attorney General for Antitrust Richard W. McLaren to say that imports of metals and other basic materials should be encouraged to create competition for the concentrated industries here at home. Cloakroom analysts are wondering how this ties in with President Nixon's cabinet task force studying the copper price structure. This is chaired by Dr. Hendrik Houthakker, a member of the White House Council of Economic Advisers who has also indicated that the use of imports to pull down prices may be one way to create less inflation.

Jan 1, 1970

By C. C. Harris

The characteristics of some common size distribution equations are critically discussed. A generalized form of several well-known size distribution equations is obtained from a differential equation describing statistical distributions. The equation contains three parameters and can describe the major features of size distributions in the fine and the coarse size regions. A graphical method for its implementation is provided. The application of this and other equations to sets of data are compared both for the quality of fit and from a comminution kinetics viewpoint. If a narrow size range of a brittle material is broken sufficiently to obliterate the feed sizes, but not so severely that excessive secondary breakage occurs, a plot of cumulative fraction by weight undersize (Y) vs. sieve size (X) on a log log grid (sometimes called the Gates-Gaudin-Schuhmann plot)1-3 gives a straight line of slope ~ 1 over much of its range. On closer inspection, deviations in the extreme coarse range covering perhaps 10 to 30% of the total sample may be apparent (frequently, a change in slope from ~ 1 to a value different from unity) together with over-all slight irregular departures from a smooth line. One model of breakage postulates that the same fracture pattern persists throughout all size ranges.4 The fracture pattern is characterized by the slope of the line on a log log grid. Accordingly, a distribution of sizes broken in the manner specified earlier is expected to produce a size distribution having the same slope as that of a broken narrow size range. Additionally, the slight irregularities mentioned above should even out in the summation process, giving a smooth straight line of slope ~1 on a log log plot. This idealized state of affairs does not, however, describe the distribution of a multi-event process such as that for a tumbling mill product. On the average, these curves (plotted again log log) tend to have a slope in the fine region different from and usually less than unity,5 while the coarse size region curves with increasing slope for cases of mild reduction, and with decreasing slope when moderate or severe size reduction has occurred. In addition, there are usually slight irregular deviations from a smooth curve. Most curves display two distinct regions — fine and coarse — and a few curves show one or more intermediate regions. Feed size studies6,7 show an effect which theory is required to explain. For the same material, mill loading and other operating conditions, and the same time of grinding, plotting the dimensionless ratios Y vs. X/(feed size) does not reduce the size distribution data to the same curve. Y vs. X does not correlate the coarse region, but it can provide a crude correlation of the fine region which improves as size diminishes and as grinding time increases. The size distribution in the coarse region is somewhat more dependent on the feed size than is the distribution in the fine region wherein the degree of dependence diminishes as time proceeds; the distribution of sizes in the fine region are determined largely by the nature of the material and the comminution conditions. A comprehensive model of comminution must recognize that several different patterns or modes of breakage can occur in a mill; 5,8,9 that there can be some selection in that some size ranges are broken more than others; and that, while some particles may be the product of a single fracture event, or may even remain unbroken, others result from multiple rebreak-age. Thus, breakage in a tumbling mill is more complex than the Schuhmann4 model admits in that several different types of comminution micro-events* occur rather than just one type, and these events, though different in size scale, are of the same overall pattern as that which is visualized by the model. The concept of an average comminution micro-event has, therefore, a mathematical rather than a physical connotation, at least for tumbling milling. Equations with which to describe particle size distributions have been sought for over half a century.10-13 No equation presently in general use was first derived from an analysis of the statistical mechanics of breakage; whatever theoretical basis the existing

Jan 1, 1969

By Klaus Schwerdtfeger

The rules of solution of oxygen from H2O-H2-He gas and of nitrogen from N2-H2 gas in shallow melts of liquid iron were measured at 1610o and 1600o C, respectiuely. Concentration profiles were detemined in the liquid iron. Tire rate data indicate that the solution process is controlled by diffusion in the iron melt. The diffusivities for oxygen and nitrogen in liquid iron, as calculated from the present data, are DFe-o = (12 ± 3) < 10-5 sq cm per sec and DFe-N = 11 ± 2) X 10-5 sq cm per sec at the temperatures employed. AN attempt was made by Shurygin and Kryukl to measure the diffusivity of oxygen in liquid iron. In their experiments a silica disc was rotated in liquid iron containing oxygen, and the rate of formation of liquid iron silicate was measured. Assuming that the rate of dissolution of silica is controlled by diffusion of oxygen in the iron, the oxygen diffusivity was computed from the rate data giving Dfe-0 = 6.1 X 5 sq cm per sec at 1600°C. Although this value seems to be of the right order of magnitude, there is no proof of the correctness of the assumptions involved in the interpretation of these rate data. The oxygen concentration in the iron at the iron-iron silicate interface was taken to be that in equilibrium with the silica-saturated silicate melt. That is, it was assumed that no concentration gradient existed in the liquid silicate. This is a questionable assumption, unless it is proved that the thickness of the silicate layer is very much smaller than that of the diffusion boundary layer in the iron. Furthermore, Shurygin et al.1 used the Levich equation2 to interpret their rate data. This equation was derived for mass transfer between a solid disc and a single-phase liquid. The hydrodynamic and diffusion boundary layers in the iron stirred by a disc, via coupling of the silicate melt, may be appreciably different from those predicted by Levich&apos;s derivations. In the present work the diffusivities of oxygen and nitrogen in liquid iron were measured at 1610" and 1600oC, respectively. EXPERIMENTAL METHOD Iron melts contained in high-purity gas-tight alumina crucibles were reacted with H2O-H2-He gas for the determination of the oxygen diffusivity and with N2-H2 gas for the determination of nitrogen diffusivity. At the end of the reaction period, the samples were quenched in a cold H2-He gas stream at the top of the furnace. Oxygen or nitrogen contents in the iron were determined by chemical analysis. Two different types of diffusion experiments were perforxed. To determine concentration profiles, a few rate measurements were made using 4-cm-deep melts. The solidified samples were sliced into discs and each disc was analyzed for oxygen or nitrogen. In another series of experiments, oxygen or nitrogen was diffused into shallow melts (about 0.5 to 1 cm in depth) and the total sample was analyzed to obtain an average concentration of the diffusate. In most experiments, 4- to 5-mm-ID alumina crucibles were used. Some experiments were also made in smaller (3 mm) and larger (7 mm) diam crucibles. This variation in diameter caused no difference in the reaction rate, within the limits of experimental uncertainty. To promote the establishment of a stable density profile in the melt, all the samples were suspended in the lower end of the hot zone so that the top of the melt was hotter by a few degrees. Molybdenum wire resistance heating was used. The reaction tube of the furnace was a gas-tight recrystal-lized alumina tube. In most experiments the furnace was heated by an ac power supply. To check the possibility of inductive stirring, some experiments were carried out in a dc operated furnace, with essentially the same results. The temperature of the furnace was controlled automatically in the usual manner. The temperature was measured with a Pt/Pt-10 pet Rh thermocouple and is estimated to be accurate within ±5°C. The iron used was prepared by melting and vacuum-carbon deoxidizing electrolytic "Plastiron" in a zir-conia crucible. The main impurities are: Si 0.004 pct P, S <0.002 pct Cr 0.005 pct N 0.001 pct Zr 0.002 pct O 0.003 pct Mn 0.004 pct C 0.002 pct The gas composition was controlled by constant pressure head capillary flowmeters. Oxygen was removed from the gas mixture by passing it through columns of platinized asbestos (450°C) and anhydrone. Selected H2O contents were obtained by passing the purified gas through oxalic acid dihydrate-anhydrous oxalic acid mixtures held at constant temperature in a water bath. Water vapor pressure data for the oxalic acid dihydrate-anhydrous oxalic acid equilibrium were taken from the 1iterature.3 The flow rate used was about 1.5 liters per min. The whole system was checked for tightness at regular intervals.

Jan 1, 1968

By Clarence Fenner

THE manufacture of optical glass is a process that demands careful regulation and control at all stages in order that satisfactory results may be obtained. The product, to serve its purpose, must meet stringent requirements, which can be assured only by careful procedure in manufacture. During the greater part of the time that a pot of glass is in the furnace, temperatures should be kept within certain rather narrow limits; a departure on either side is likely to be detrimental to the glass and may result in total loss. If the temperature during melting and fining be low, the melt is likely not to fine properly and the glass will contain quantities of bubbles, or "seed," or it may become milky and unfit for use; too high a temperature, on the other hand, is severe on the pot and may cause it to leak or cast stones, or the increased solution of pot material in the melt may acid to the color of the glass and decrease its transmission. Moreover, variations in the working temperature will mean variations in the amount of selective volatilization and, consequently, variations in optical properties from pot to pot. Furthermore, in the closing stages of furnace treatment, the melt is cooled until a certain degree of stiffness is attained, when the pot is withdrawn. The quality of the glass-its freedom from striae and bubbles-will depend in large measure on whether the temperature to which cooling has been carried is suitable. For each type of glass there is a narrowly restricted range of temperature to which each pot of the given type should be cooled before withdrawal. A quick and reliable method of measuring temperatures is, therefore, of the first importance. In the optical-glass work conducted by the staff of the Geophysical Laboratory during the period of the war, much attention was given to the clatter of determining what methods would meet the requirements. This article will deal with these investigations and with the application of the results to actual practice at various plants. At the. time that the work of the Geophysical Laboratory was begun at the Bausch & Lomb plant, each melting furnace was equipped with

Jan 7, 1919

Until the end of 1960, the small primary aluminum industry in Australia was run by the government. The entire operation was at Bell Bay on the north coast of Tasmania. It consisted of an alumina plant and smelter, owned jointly by the Commonwealth and the State of Tasmania. Apparent domestic demand that year was about 48,000 long tons; 11% thousand came from Bell Bay; the rest was imported. By March 1964, Australia had two fully integrated aluminum companies. The government has stepped out of the picture and the key word of the industry from bauxite to metal is "growth." Present annual capacity of the two companies for making aluminum metal totals 92,000 long tons a year. Australian demand is about 60,000 tons. By 1968 Australian consumption should be 90,000 tons and by 1970 it is expected to reach 107,000 long tons per year. Export markets for bauxite, alumina and metal are developing.

Jan 10, 1964

By J. B. Dilworth

The word ".development," as used in connection with mining, is a rather general term and in most instances must be qualified or explained before the exact thought in the mind of the user is made clear. For instance, by the development of a mining district is often meant its entire facilities of mineral production, such as railroads, towns, mine plants, etc. In speaking of the development of a property its prospecting by test pits or diamond drill borings may be referred to; or it may be the mines, strip pits or quarries from which the coal, ore or rock is won. Rut, as a rule, when the development of an individual mine is spoken of the idea in mind is the system of underground workings by means of which the mineral is recovered and transported to the surface. It is this character of development that is considered here. The discussion will be confined to the ordinary room-and-pillar system of mining practically horizontal coal seams that is used in most bituminous coal mines in this country, and to only two phases of this subject; viz., what is properly included under the head of "Development" as it appears on the books of a coal company or the inventories of an examining engineer, and how its " value " should be determined by the accountant or engineer. No absolute rule or definite agreement covers these points, yet these questions are far more than academic. Development is often an important part of a mining company&apos;s assets, affecting the amount of its invested capital (and hence its rate of taxation under present Federal income tax laws) as well as the value of its total assets and the amounts chargeable to cost of coal and to depreciation. Mine Development Account Perhaps the majority of mine accountants will agree that the mine development account is that capital account which shows the extraordinary expenditures incurred in opening and expanding the underground workings of a mine until it has reached its normal production, the expenditures being those made for shafts, slopes, rock tunnels, drift mouths and such relatively permanent work; also payments over and above ordinary mining costs made for driving entries, air courses and break-through; for

Jan 1, 1922

By McIntosh F. Galbraith

This paper describes the use of the magnetometer, under geological direction, in exploration of the Sudbury nickel district. The writer&apos;s experience at Falconbridge has led him to the belief that only through detailed work, and by careful correlation of both geological and geophysical results, can geophysical prospecting methods be applied successfully to mining exploration problems. It is hoped that the basic technique described in the paper will be found to have general application.

Jan 1, 1942

Rutile – Zircon Mining on East Coast Surfing Beaches – Rutile-Zirconium Producing Companies in Australia

Jan 10, 1964

By C. S. Corbett

There is much comment at present in the ranks of the oil industry regarding unit operation of oil fields and the benefit that would accrue if it could be extensively applied. It seems certain that, as an immediate corrective of the present situation, overproduction could be effectively curtailed with all the advantages of proper conservation of petroleum resources and with no important loss to anyone connected with the industry. Unit Operation in Certain Foreign Fields Many an oil operator in America would doubtless like to have exclusive control of one or more oil-bearing structures for development in accordance with the economic position of the industry and especially in accordance with the best production practice known. A few operators now have this privilege, particularly in certain foreign fields, and are following lines of procedure which show that they are aware of the great opportunity that is theirs. We find in an article by Professor Strigeoff,1 and in a paper read by Captain Comins2 before the American Petroleum Institute, the outlines of procedure adopted, respectively, by the Soviet Government for the nationalized Russian oil fields and by the Anglo-Persian Oil Co. for its fields in Persia. Comprehensive plans for the unit operation of other oil fields may have been described publicly but no such descriptions have come to the attention of the writer. New fields are coming more and more into the hands of single operators or of a few who control large activities and who appreciate fully the need for cooperative action and are willing to forego the lure of a large quick profit from high flush production in order to secure the advantage of better stabilization in the industry and a larger though more deferred profit by operating the field as a unit. Much can be done toward efficient development of an oil field controlled by a few operators who are willing to cooperate for that purpose, but the best result can be obtained only by pooling their interests in the field

Jan 1, 1930

By E. V. Foran

TheRe are many factors which control the ultimate production of oil and gas from a producing formation and the rate at which this production is obtained from any of the producing wells in the formation. The most important of these, and the one over which the greatest control can be exercised, is the differential pressure existing between the formation and the well bore. In producing any well by means of the gas-lift, it may be possible to change the flow tubing in a number of ways or vary the volume of circulating gas or air used for flowing the well, but if these operations, regardless of their magnitude, do not change the differential pressure between the producing sand and the well bore, they will in no way change the production of the well. If this statement is accepted as a fact, then all gas-lift or air-lift installations should be designed with but one object in view; namely, a means by which we can economically control very wide ranges of differential pressures between the formation and the well bore. Factors of Production In gas-lift production from any given formation, there are four major factors which govern the magnitude of the differential: (I) the depth of the well; (2) type and size of flow tubing; (3) volume of the circulating air or gas, and (4) physical properties of the oil-gas mixture after it has reached the well. The first of these factors is uncontrollable and does not vary. The other three are controllable within certain limits. The degree to which the last three factors can be controlled will cntircly govern the length of life of the well while on the lift, the lifting cost, and the daily production. It will also govern to some extent the ultimate production from the wells or leases producing by this method. These four factors will be discussed in detail in another part of this paper. Before proceeding further, a review of the present general practice in Texas, elsewhere than in the Gulf Coast region, will be given.

Jan 1, 1928

by their overdogmatic picture of geology and their resulting drastic oversimplification and idealization of geologic features. I am in hearty disagreement with the recommendation that geophysics should be done by cooperative work between a geologist and a geophysi-cist. That arrangement would be comparable to doing petrography by having a physicist at the microscope and a geologist sitting by his side. The interpretation of the geological significance of geophysical data can be done efficiently only by a physicist who has become also a good geologist or by a geologist who is also a good geophysicist. Less Well-trained Men The rank and file, composing perhaps two-thirds of the personnel of exploratory geophysics, is not, and should not be, composed of highly trained men. The routine, stereotyped character of the work and the impossibility of promotion of more than a few from these lower ranks even under the best circumstances justify companies in filling the bulk of these rank and file positions with men having only a bachelor&apos;s degree at the most. There can be a wide range of training for such positions, although certain lines of study are preferred for certain kinds of work, and different employers have different preferences. For work in gravitational and magnetic prospecting, first preference will be for men having geological training and second for men with civil engineering training. In seismic work, men with geological training are preferred by some employers for computers; physicists, electrical engineers and all whose technical education has covered radio circuits are preferred for the other technical positions. Collegiate training in geophysical prospecting brings no preference and by many employers is given a slightly inferior rating. One large company seldom hires men who have just graduated with a major in geophysical prospecting. This prejudice is based on the reasoning that much of what is learned in college is obsolete or obsolescent, that most of the techniques learned in college will have to be unlearned, because different from those used by the employing company, and that in the long run additional courses in basic physics, mathematics and geology are of more value to a man than the courses on geophysical prospecting. DISCUSSION [This discussion refers to the five papers beginning on page 23 and ending on page 74.1 L. W. Blau,* Houston, Texas.—I have had some rather sad experiences with forecasting. For example, I could not foresee 10 years ago my present occupation, and I do not profess to be able to look ahead 10 years and tell anyone what he will be doing then. Referring to the point raised in the discussion, I do not know, for example, what the price of oil will be 10 years from now. If an appreciable number of

Jan 1, 1940

by their overdogmatic picture of geology and their resulting drastic oversimplification and idealization of geologic features. I am in hearty disagreement with the recommendation that geophysics should be done by cooperative work between a geologist and a geophysi-cist. That arrangement would be comparable to doing petrography by having a physicist at the microscope and a geologist sitting by his side. The interpretation of the geological significance of geophysical data can be done efficiently only by a physicist who has become also a good geologist or by a geologist who is also a good geophysicist. Less Well-trained Men The rank and file, composing perhaps two-thirds of the personnel of exploratory geophysics, is not, and should not be, composed of highly trained men. The routine, stereotyped character of the work and the impossibility of promotion of more than a few from these lower ranks even under the best circumstances justify companies in filling the bulk of these rank and file positions with men having only a bachelor&apos;s degree at the most. There can be a wide range of training for such positions, although certain lines of study are preferred for certain kinds of work, and different employers have different preferences. For work in gravitational and magnetic prospecting, first preference will be for men having geological training and second for men with civil engineering training. In seismic work, men with geological training are preferred by some employers for computers; physicists, electrical engineers and all whose technical education has covered radio circuits are preferred for the other technical positions. Collegiate training in geophysical prospecting brings no preference and by many employers is given a slightly inferior rating. One large company seldom hires men who have just graduated with a major in geophysical prospecting. This prejudice is based on the reasoning that much of what is learned in college is obsolete or obsolescent, that most of the techniques learned in college will have to be unlearned, because different from those used by the employing company, and that in the long run additional courses in basic physics, mathematics and geology are of more value to a man than the courses on geophysical prospecting. DISCUSSION [This discussion refers to the five papers beginning on page 23 and ending on page 74.1 L. W. Blau,* Houston, Texas.—I have had some rather sad experiences with forecasting. For example, I could not foresee 10 years ago my present occupation, and I do not profess to be able to look ahead 10 years and tell anyone what he will be doing then. Referring to the point raised in the discussion, I do not know, for example, what the price of oil will be 10 years from now. If an appreciable number of

Jan 1, 1940

By Edward B. Cook

The installation of the Gayley dry-air process appealed specially to the management of the Warwick Iron & Steel Go., for the reason that for fifteen years records had been kept at the works of the company, showing the amount of water entering the furnace in the form of aqueous vapor, and careful observations had been made of its effect upon the working of the furnace. Some years had proved much worse in their effect than others, on account, not only of excessive moisture, but also of great variation in the moisture from day to day, and sometimes within a few hours. It had been found impossible to make a satisfactory percentage of high-silicon foundry-iron in summer, even on high fuel; and for some years the endeavor had been made so to arrange the sales that, during July and August, only a small percentage of the iron produced would be required to carry more than 2 per cent. of silicon. Our larger furnace, running on basic iron, year after year, produced in February a tonnage 20 per cent. higher than in August, 011 a much lower fuel-consumption, while, at the same time, the summer months were marked by " messes," tuyeres closed by slips, and other irregularities, constituting serious additional business losses. It will be easily understood, therefore, that the records made at the Isabella furnace after the installation of the dry blast in 1904 possessed special interest, and were closely watched by us. On the basis of our own experience, we argued that if the moisture could be kept low, and also uniform, the cost of installation would be more than justified. The subject was brought before our Board of Directors in the fall of 1905; and in the spring of 1906 it was decided to install a plant of sufficient

Jan 1, 1909

By A. E. Perkins

fractured ingot will show a complete diagonal structure. If the temperature is lowered, the equi-axed zone is larger and the pine tree growth is less. A small ingot, though, is prone to this columnar structure, even though the casting temperature is kept down. The speed of cooling after solidification is slower in the hollow ingot than in the solid, therefore the granulation, which takes place after the crystals have formed from the liquid metal, is apt to produce larger grains than in the solid ingot. This is not a detriment. The original crystal size is of much more importance. The size of the grains due to this granulation constantly varies in response to mechanical work and subsequent heat treatment. Surface weakness, as shown by seaming and checking on the exterior when working or by cracking in hardening, is in some measure the result of the surface stresses of the ingot when cast. The temperature of the ingot mold or speed of freezing of the exterior of the ingot is of great importance and much seamy and cracked steel is caused by a too quickly cooled skin. Ingots that are turned or milled all over will not seam very much in working, in fact they are practically free from seams, whereas an ingot rolled without a preliminary machining operation is full of seams and cracks, some long and some short. It has been said that these short seams and cracks in the surface of the bar are the result of elongated depressions in the surface of the ingot and that if an ingot is cast very smooth it should give fewer surface defects. This is partly true, but an ingot cast very hot and having a very smooth skin will crack and seam very badly in the mill, as will the surface of an ingot poured very cold, which is very crinkly, because of the low temperature of the metal. The cause of the cracks and seams in one is not the cause of the cracks and seams in the other. The tube method of hollow drill steel manufacture is superior to the older method because of: (1) Greater freedom from external and internal straining; (2) the inherent small crystal size; (3) absence of harmful segregation, resulting in weakness of wall of hole. (4) less liability for steel to crack in inside of hole during forging or hardening; (5) toughening effect, arising from mild steel wall of hole limiting the intense hardening on quenching. Breakage and Heat Treatment or Rock-drill Steel By A. E. Perkins, Pittsburgh, Pa. Actual figures showing the superiority of one section or another are difficult to obtain. In a given size of steel, however, the cruciform sec -tion shows the most breakage; it is inherently a weak section. It contains less steel per foot than any other standard section of the same size and when rolled the wings tend to cool off setting up cooling stresses.

Jan 1, 1922

By C. M. Schwartz, J. R. Bridge, D. A. Vaughan

THERMAL expansion coefficients of a uranium were originally reported&apos; on the basis of X-ray diffraction measurement of lattice constants at 25°, 300°, and 650°C. These data have been reproduced by Katz and Rabinowitch.&apos; CuK radiation had been used in this work, with consequent crowding of the patterns. Considerable overlap of the back-reflection lines was observed as the temperature was raised. Subsequent reexamination of the data led to the conclusion that errors had resulted from failure to obtain unequivocal indexing of the high angle reflections at elevated temperatures. The measurements have been repeated, using FeK radiation, which provided sufficient dispersion to assure proper indexing of the reflections, at each temperature level. The unit cell dimensions were re-determined at ten temperatures, from 25" to 650°C. Schuch and Laquer easured the macroscopic contraction from room temperature down to —253°C, and reported a negative value from —210" to —253°C; they suggested the possibility of the occurrence of a phase change. In the present work, the lattice constants of uranium have been measured down to —253°C, to test this hypothesis. Filings were prepared from a single piece of pure uranium bar stock. They were carefully cleaned with a magnet and pickled in nitric acid to remove traces of iron from the file. They were then annealed at 600°C in a sealed evacuated silica tube. The annealed filings were pickled in strong nitric acid to remove any oxide layer, washed in water and alcohol, quickly dried, and sealed in evacuated thin-walled silica capillary tubes. If properly sealed, the sample could be heated to the a-ß transforination temperature without significant buildup of the diffraction pattern of oxide. The high temperature X-ray diffraction camera was modified from the design of Hume-Rothery and Reynolds.&apos; The thermocouple used to record the specimen temperature was calibrated from lattice-constant measurements of a standard silver specimen, using the Hume-Rothery and Reynolds values for silver over the temperature range from 25" to 700°C. Temperatures were reproducible to 210°C. Temperatures to —210°C were attained by passing precooled gas over the sample. The gas from the cooling train was directed over the sample capillary tube and thermocouple by means of a chimney of 1-mil polystyrene. The 36-gage Cu-constantan thermocouple had been calibrated by

Jan 1, 1957